Uplink pilot channel transmission to reduce latency of circuit switched fall back

Abstract

A method of wireless communication includes initiating a specific call type and transmitting a first random access preamble via a first random access preamble channel when initiating the specific call type. The method also includes transmitting a second random access preamble via a second random access preamble channel when initiating the specific call type. The second random access preamble is transmitted without waiting for a response to the transmitted first random access preamble

What is claimed is: 
     
         1 . A method of wireless communication, comprising:
 initiating a specific call type;   transmitting a first random access preamble via a first random access preamble channel when initiating the specific call type; and   transmitting a second random access preamble, without waiting for a response to the transmitted first random access preamble, via a second random access preamble channel when initiating the specific call type.   
     
     
         2 . The method of  claim 1 , in which the first random access preamble channel is a same channel as the second random access preamble channel. 
     
     
         3 . The method of  claim 1 , in which the second random access preamble channel is different from the first random access preamble and is consecutive to the first random access preamble channel. 
     
     
         4 . The method of  claim 1 , in which the first random access preamble is a same preamble as the second random access preamble. 
     
     
         5 . The method of  claim 1 , in which the first random access preamble and the second random access preamble are transmitted at different power levels. 
     
     
         6 . The method of  claim 1 , in which the first random access preamble and the second random access preamble are transmitted at a same power level. 
     
     
         7 . The method of  claim 1 , further comprising transmitting a connection request in response to receiving an acknowledgment for at least one of the first random access preamble, the second random access preamble, or a combination thereof. 
     
     
         8 . The method of  claim 1 , in which the specific call type is a circuit switched fall back (CSFB) call. 
     
     
         9 . The method of  claim 1 , in which the specific call type is an emergency call. 
     
     
         10 . An apparatus for wireless communication, comprising:
 means for initiating a specific call type;   means for transmitting a first random access preamble via a first random access preamble channel when initiating the specific call type; and   means for transmitting a second random access preamble, without waiting for a response to the transmitted first random access preamble, via a second random access preamble channel when initiating the specific call type.   
     
     
         11 . The apparatus of  claim 10 , in which the second random access preamble channel is different from the first random access preamble and is consecutive to the first random access preamble channel. 
     
     
         12 . The apparatus of  claim 10 , in which the first random access preamble is a same preamble as the second random access preamble. 
     
     
         13 . The apparatus of  claim 10 , in which the first random access preamble and the second random access preamble are transmitted at different power levels. 
     
     
         14 . The apparatus of  claim 10 , further comprising means for transmitting a connection request in response to receiving an acknowledgment for at least one of the first random access preamble, the second random access preamble, or a combination thereof. 
     
     
         15 . The apparatus of  claim 10 , in which the specific call type is a circuit switched fall back (CSFB) call. 
     
     
         16 . A computer program product for wireless communication in a wireless network, comprising:
 a non-transitory computer-readable medium having non-transitory program code recorded thereon, the program code comprising:   program code to initiate a specific call type;   program code to transmit a first random access preamble via a first random access preamble channel when initiating the specific call type; and   program code to transmit a second random access preamble, without waiting for a response to the transmitted first random access preamble, via a second random access preamble channel when initiating the specific call type.   
     
     
         17 . The computer program product of  claim 16 , in which the second random access preamble channel is different from the first random access preamble and is consecutive to the first random access preamble channel. 
     
     
         18 . The computer program product of  claim 16 , in which the first random access preamble is a same preamble as the second random access preamble. 
     
     
         19 . The computer program product of  claim 16 , in which the first random access preamble and the second random access preamble are transmitted at different power levels. 
     
     
         20 . The computer program product of  claim 16 , in which the program code further comprises program code to transmit a connection request in response to receiving an acknowledgment for at least one of the first random access preamble, the second random access preamble, or a combination thereof. 
     
     
         21 . The computer program product of  claim 16 , in which the specific call type is a circuit switched fall back (CSFB) call. 
     
     
         22 . An apparatus for wireless communication, comprising:
 a memory; and   at least one processor coupled to the memory, the at least one processor being configured:
 to initiate a specific call type; 
 to transmit a first random access preamble via a first random access preamble channel when initiating the specific call type; and 
 to transmit a second random access preamble, without waiting for a response to the transmitted first random access preamble, via a second random access preamble channel when initiating the specific call type. 
   
     
     
         23 . The apparatus of  claim 22 , in which the first random access preamble channel is a same channel as the second random access preamble channel. 
     
     
         24 . The apparatus of  claim 22 , in which the second random access preamble channel is different from the first random access preamble and is consecutive to the first random access preamble channel. 
     
     
         25 . The apparatus of  claim 22 , in which the first random access preamble is a same preamble as the second random access preamble. 
     
     
         26 . The apparatus of  claim 22 , in which the first random access preamble and the second random access preamble are transmitted at different power levels. 
     
     
         27 . The apparatus of  claim 22 , in which the first random access preamble and the second random access preamble are transmitted at a same power level. 
     
     
         28 . The apparatus of  claim 22 , in which the at least one processor is further configured to transmit a connection request in response to receiving an acknowledgment for at least one of the first random access preamble, the second random access preamble, or a combination thereof. 
     
     
         29 . The apparatus of  claim 22 , in which the specific call type is a circuit switched fall back (CSFB) call. 
     
     
         30 . The apparatus of  claim 22 , in which the specific call type is an emergency call.